Drilling machine switch



May 23, 1939. R. K. JEFFREY DRILLING MACHINE SWITCH Original Filed May14, 1954 5 sheets-Sheet l fivvE/vTo/i: ROBERT K. JEFFREY,

BY MM, MIM

May 23, 1939. R. K. JEFFREY 2,159,089

DRILLING MACHINE SWITCH Original Filed May 14, 1934 3 Sheets-Sheet 2 53Eye Gttomeg May 23, 1939. R. K. JEFFREY DRILLING MACHINE SWITCH 3Sheets-Sheet 3 Original Filed May 14, 1934 3110mm 120mm K. JEFFREY.

(Ittorneg Patented May 23, l93

UNITED STATES PATENT ()FFICE DRILLING MACHINE SWITCH Robert K. Jeffrey,Bexley, Ohio, assignor to The Jeffrey Manufacturing Company, acorporation of Ohio 11 Claims.

The present invention relates to an improved switch particularly usefulwith portable drilling units of the manually supported type although itmay have a general application.

One of the objects of the invention is the provision of an improved andcompact but highly efficient circuit controlling switch for a motor,such as the motor of a drilling machine.

A further object of the invention is the provision of improved andefiicient electric switch mechanism for controlling an electric motor ofa drilling machine, including a magnetic blowout which acts to blow outarcs as the circuit is simultaneously broken in two places by a snapaction.

Other objects of the invention will appear hereinafter, the novelfeatures and combinations being set forth in the appended claims.

In the accompanying drawings,

Fig. 1 is a wiring diagram showing the electrical connections from thesource of power to the motor through the electric switch;

Fig. 2 is a sectional plan view of a portion of a drilling machinecomprising the switch housing, switch and operating mechanism;

Fig. 3 is a sectional view of the control switch taken on the line 33 ofFig. 2 looking in the direction of the arrows;

: Fig. 4 is a fragmentary sectional elevational view of the switchmechanism and the mechanism for efiecting the operation thereof manu-:ally to closed position and automatically to open position;

Fig. 5 is a sectional view taken on the line 5-5 of Fig. 4, looking inthe direction of the arrows, and showing the relative positions of theswitch operating handle and the switch yoke when the switch is closed;

Fig. 6 is a view similar to Fig. 5, but showing the relative positionsof the switch operating handle and switch yoke when the switch is inopen position;

Fig. "I is a sectional view of the switch taken 45 on the line 1 1 ofFig. 4, looking in the direction of the arrows;

Fig. 8 is a View similar to Fig. 7, but showing the switch in closedposition, and Fig. 9 is a sectional view somewhat similar to Fig. 4 butwith certain parts broken away to show more clearly the elements of theswitch.

This application comprises a division of my application for Drillingmachines, Serial No. 55 725,504, filed May 14, 1934, and of myapplication for a Drilling machine switch, Serial No. 59,421, filedJanuary 16, 1936.

Referring more particularly to the drawings, it will be observed thatthe switch is illustrated as controlling a drilling machine parts ofwhich are shown in the drawings. Said electric controlling switch isVery compactly arranged in a flame-proof casing C, as shown in Fig. 2.

Mounted in the tubular extension 48 of the casing 0r compartment C is abushing 52 to serve as a journal bearing for the cup shaped sleeve 49which is secured by means of the pin 50 to the inner end portion of thehollow switch operating handle 41. The bushing 52 is secured to thetubular extension 48 by means of the pin shown at 48 A portion of thebushing 52 extends inwardly to form fixed abutments 52 and 52 as shownin Figs. 5 and 6, which abutments are stationary relative to thesupporting casing or frame of the drilling machine.

The outer end of the sleeve 49 is provided with an annular flange 49which is adapted to abut against the outer end of the bushing 52 asshown in Fig. 2. A retaining washer ll!) and a snap ring H9 serve tohold the annular flange 49 in its position against the outer end of thebushing 52.

The outer end of the tubular support 48 is recessed not only to provideannular seats for the washer 9 and the snap ring H9 but also the innerend of the coil spring 51 which inner end is secured to the tubularsupport 48. The outer end of the spring 51 is secured at 58 to thetubular handle 41' as shown in Figs. 2 and 4. The inner end 5| of thesleeve 49 is provided with an extension 49' which is provided with aspring seat 5W (Figs. 5 and 6), and a movable abutment 5l When thehandle 41 is released the spring 5'! acts to move the abutment carrier49 to a position shown in Fig. 6.

Projecting axially from the center of the plate 5| as shown in Figs. 4,5 and 6, is a bearing 54 about which is coiled the intermediate portionof the spring 60, one end of which at 60 rests against the seat 5F andthe other end of which at 60 bears against the yoke 53 one end of whichis journaled on the bearing 54 and the other end of which is providedwith a shaft 54 which is journaled in the bearing 55 as shown in Fig. 4.The shaft 54 is in axial alignment with the bearing 54.

The yoke 53 is connected to electric switch mechanism for controllingthe starting and stopping of the electric motor by means of the circuitsand connections diagrammatically illus-,

trated in Fig. 1. When the handle 41 is turned in one direction theswitch will be closed and the motor started to operate the drillingmachine. The rotation of the handle Al to close the switch places suchtension in the spring 51 that when the handle 41 is released by theoperator the spring 51 will act automatically to restore the switch toits open position and thereby effect stopping of the motor.

Inasmuch as it is desirable to open the switch with a snap action oreffect very quick separation of the contacts of the electric switch inorder to reduce the arcing to a minimum when the circuit of the electricmotor is broken, compactly arranged automatic switch operating mechanismis mounted in the compartment C and connected to the handle 41 as shownin Figs. 2, 3, 4, 7, 8 and 9.

The switch mechanism is mounted between blocks of insulating material lland d3 (Fig. 3) which are secured to the bosses 96 and 99 by means ofthe screw-threaded ends of the cap screws 96 and 98 and the insulatingspacing tubes 91 and 66.

The spacers 66 may be integral with the insulating block H and eachprovided with a depending support 66 (Fig. 9) provided with alignedopenings for receiving the inner ends of laterally projecting bearings65, 65 which may be pinned to the support 66 as indicated at 55 in Fig.9.

As shown in Figs. 3, 7, S and 9, insulating blocks 5| are provided withupwardly opening slots or recesses 64 to fit over the bearings 65 fromthe underside of the latter. The insulating blocks iii are rigidlyconnected by the transverse insulating cross-piece 6!. Between theblocks 6! and parallel to the crosspiece 6! is mounted a transverse pin59 having a groove ll? intermediate its ends for receiving the lower endiii of. the spring Bil, the upper end of which is hooked at H throughthe opening 12 at the upper central portion of the yoke 53.

Each of the insulating blocks 6! Carries a metallic strip or finger 62the lower end of which is pinned at 83 to the copper contact 63. At theupper end of each metal strip 652 is a square hole adapted to fitloosely over the squared head llof a screw inserted in the upper portionof the block 6| as shown in Figs. '7, 8 and 9. This arrangement preventsthe contact carrying strips or fingers 62 from swiveling in its ownplane but a limited movement of the strip 62 transversely of its ownplane is permitted to secure a wiping action of the contact 63 againstthe metal plate l3 when the switch is moved from its open position inFig. 7 to its closed position in Fi 8.

A pin 19 secured to each block 6! projects through a hole in the strip62 intermediate its ends. Each pin I9 is provided with a collar to witha spring 8| between the same and the outer surface of the strip 62 asshown in Figs. 7 and S. A cotter pin 82 holds the collar in place. Whenthe block Si is moved to the position shown in Fig. 8 the spring Blholds the contact 63 yieldingly against the metal plate 13. As shown inFigs. 7 and 8, the metal plate if; is

secured by means of the cap screw i l to the base block 16 of insulatingmaterial which may be integral with the insulating block 71.

By referring to Fig. 9, it will be seen that spaced-apart electricterminals may be afforded by the metal plates l5, 15 secured to themetal plates 13, 13 by means of the screws l5, 75'.

Electric terminals 62 [-32 are riveted to the contact carrying strips 62as shown at 62 62". As shown in Fig. 1, the switch is two-pole in thatone electric conductor extends through the contacts 63, it and anotherconductor extends through the contacts 63', '13, said conductors be ingrespectively connected to the supply mains.

In order to minimize arcing during operation of the switch mechanism,there is mounted between the insulating blocks H and 93 within the spacebetween the base blocks l6, it, a blow-out coil as having a fluxconcentrating iron core 84 the ends of which project through openingsinto insulating blocks 84 84 so as to occupy positions closely adjacentto the points of engagement between the contacts 63 and the plates Asshown in Fig. 1 the winding of. the blowout coil 84 is connected in themotor circuit and in series with the two sides of the double-poleswitch. When the switch is open the blow-out coil acts to lengthen thearcs between the contact 53 and the plate '13 aiding the disruption ofsuch arcs.

As a precaution against the burning of any of the parts when such arcsare formed upon the breaking of the circuits at the switch contacts inthe compartment C, plates !35, l35 of asbestos or other non-inflammablematerial are secured at M5, M5 to the outer surfaces of the base blocksit at the sides of the switch mechanism as shown in Fig. 4. The securingmeans at M5, M5 may be screws extending into the blocks 18 as shown inFigs. '7 and 8. The end blocks 84 84 of the blow-out coil are alsopreferably made of asbestos or other non-inflammable material to protectcoil 8 3.

A safety fuse 35 is mounted between clips 92, 92 and connected in themotor circuit as shown in Fig. 1. The compartment C in which the switchmechanism is mounted is provided with a cover its screw-threaded toclosed position and sealed in closed position as illustrated at I20 inFig. 2. Access may be had to the interior of the compartment C forrenewal of the blown-out fuse Si by removing the cover hi5 but not untilthe seal He has been broken.

Secured to the insulating block 513 by means of the screws lfil, H3! isa plate of. insulating material provided with upper and lower extensions582 and 283 at right angles to the block 93 and extending across theouter ends of the clips 92, 9:2 as shown in Fig. 3 so as to prevent anypossibility of grounding of the clips 92, 92 through the heads of thescrews 98 to the metal frame or casing of the drilling machine. Aconnector lil as shown in Fig. 3 for the conductor i26 shown in Fig. 1may be mounted back of a curved portion M3 of the shield M l forprotection thereby.

In order properly to space the ends of the iron core S l of the blow-outcoil 8 from the switch contacts @3, H a retaining block of insulatingmaterial is riveted at 94 to the inner surface of the insulating block93 as shown in Fig. 3. The lower corners of the block 95 are suitablynotched to fit over the beveled upper edges 84 of the rectangular endinsulating blocks 84*. The latter are also clamped by means of thescrews 96 and 98 between the insulating blocks 93 and 11.

It should be particularly noted that when the cover N35 is removed theentire switch unit may be removed and taken apart for the purpose ofrepair or replacement. This is particularly true with respect to thecontact carrying mechanism because the open slots 64 permit theinsulating block 6| together with the crosspiece 6| to be removed fromthe bearings 65, 65 against the action of the spring 68. If desired, thecontact carrier may be readily detached from the hook 10 at the lowerend of the spring 68. When the retaining ring H9 shown in Fig. 4 isremoved the handle 41 may be removed from the journal bearing 52 thusdisconnecting the handle from the yoke and permitting the removal of thelatter from the bearing 55.

When all of the parts of the drilling machine are in assembled relationready for operation, the electric switch may be closed to efiectstarting of the motor by rotation of the handle 41 against the action ofthe spring 51 in an anti-clockwise direction as viewed in Fig. 5. Whenthe switch is open the yoke 53 occupies the position shown in Fig. 5 orthe position shown in full lines in Fig. 2.

When the handle 41 is rotated in an anti-clockwise direction as viewedin Fig. 5 the abutment 5| will engage the yoke 53 to swing the same fromits full line position shown in Fig. 3 toward its dotted line position.In doing so, the outer central portion of the yoke 53 engages the freeend of the spring clip I2I which is secured to the inner surface of thecompartment C as shown in Fig. 3. However, the yoke 53 clears the springclip I2I by the time that the spring 68 moves to a position to the leftof the axis of the bearing 65 as viewed in Fig. 3 whereupon the spring68 is free to act to effect closure of both of the sets of contactsdesignated 63, I3 and 63', I3 in Fig. 1. When the switch is closed theyoke 53 is held against the fixed abutment 52 with the abutment 5| heldmanually against the other side of the yoke 53 as shown in Fig. 5.Furthermore, when the switch is closed the spring 60 has one arm 60resting against the seat 5I and the other arm 60 engaging that side ofthe yoke 53 remote from the abutment 5I When it is desired to open theswitch the handle 41 is released whereupon the stored tension in thespring 51 will act automatically to move the carrier 49' in a clockwisedirection as viewed in Fig. 5 thereby continuing to move the abutment 5|away from the yoke 53. The yoke 53 moves through a small angle to aposition in engagement with the spring clip I2I due to tension in spring60, At such time the spring 60 does not have sufficient tension to movethe yoke 53 past the clip I2I. In other words, the clip I2I preventscontinued movement of the yoke 53 until a predetermined amount oftension is stored in the spring 60. The purpose of the retarding actionof the spring clip I2I is to hold the yoke 53 in such position that thespring 68 may be at the left of the axis of the bearings 65 so that theswitch will be held positively closed until it is ready to open with asnap action. That is to say, in order to prevent initial movement of thehandle 41 towards switch opening position from causing the contacts 63and 63' from separating from the plates 13, 13 the spring clip I2Icauses the spring 60 to hold the switch positively closed therebypreventing arcing which would occur when the contacts 63, 63 are movedonly a short distance from the plates 13, 13. As rotation of the handle41 continues in a clockwise direction as viewed in Fig. 4, the abutment5| moves farther away from and the abutment 5I moves closer to the yoke53, but the latter being held by the spring clip I2I causes increasingtension to be stored in the spring 60 until such tension is suflicientto overcome the holding effect of the spring clip I2I. Then the spring60 moves the yoke 53 from under the spring clip I2 I, whereupon thespring 68 moves to the right of the center of the bearing 65 as viewedin Fig. 3, whereupon the contacts 63, 63 would he suddenly and quicklywithdrawn from the contact plates 13, 13'. When the switch is in openposition the yoke 53 will rest against the abutment 52 as shown in Fig.6 and the crosspiece 6 I of the switch contact carrier will abut againstthe back of the insulating block 95 as shown in Fig. 3.

Fig. 1 shows diagrammatically the circuits and connections for theelectric drill motor and the switch for controlling the same. Theterminal hook I28 may be connected to a trolley wire in a mine to serveas the connector to the positive supply main I21 which is connected tothe plate 13, The hook I22 may be attached to the rail I3I of the minetrack to serve as the connector to the negative supply main I23 which isconnected to the contact plate 13. The motor is preferably compoundwound so that it will not race under substantially no load and yet becapable of withstanding heavy overloads without overheating.

When the switch is closed the motor circuit may be traced in Fig. 1 tothe conductor I21 through contacts I3, 63, fuse 9|, conductor I26,series motor winding 85, motor armature I4, conductor I25, blow-out coil84, contacts 63, I3 and thence to the negative conductor I23. The shuntfield coil is also energized as it is shunted across series winding 85and armature I4.

In order to protect the operator of the drilling machine the casing orframe thereof is grounded by a conductor I30 connected at its outer freeend to the rail I3I and at its inner end to the frame or casing of themachine as illustrated diagrammatically at I29 in Fig. 9. This groundingconnection may be eiiected by connecting the conductor I30 to the headof a screw in metallic contact with the metal frame of the machine.

It is thus to be seen that I have provided a very efficient, lightweight switch which will insure the opening of a circuit even underheavy load. It is well adapted for use in a hand operated coal drill, asabove described, but it is not limited to this use.

Obviously those skilled in the art may make various changes in thedetails and arrangement of parts without departing from the spirit andscope of the invention as defined by the claims hereto appended, and Itherefore wish not to be restricted to the precise construction hereindisclosed.

Having thus described and shown an embodiment of my invention, What Idesire to secure by Letters Patent of the United States is:

1. In an electric drill switch, the combination with a base ofinsulating material, of a pair of spaced-apart fixed switch contactscarried by said base, a pivoted insulating carrier, spaced-apart movableswitch contacts mounted on said car rier in co-operative relation tosaid fixed contacts to form two circuit breakers which close and opentogether, means for operating the switch including the separation of themovable contacts from the fixed contacts with a snap action, a commonblow-out coil connected in series with both circuit breakers and havingpoles at its opposite ends. and means for mounting said blow-out coil onsaid base with said poles closely adjacent the points of engagementbetween the movable contacts and the fixed contacts of said circuitbreakers to aid the said snap action in extinguishing the arcs betweenthe disengaging contacts when the switch is opened.

2. In an electric drill switch, the combination with a base ofinsulating material, of a pair of spaced-apart fixed switch contactsmounted thereon, a carrier of insulating material pivotally mounted onsaid base, movable switch contacts carried by said pivoted carrier incooperative relation to said fixed contacts to form two circuit breakerswhich close and open together, a common blow-out coil connected inseries with both circuit breakers and having end poles, means formounting said blow-out coil on said base between said fixed contactswith its end poles closely adjacent thereto, and non-inflammable platesmounted adjacent said fixed contacts at the outer sides thereof withsuch fixed contacts intervening between such plates and the end poles ofthe blow-out coil, and means for actuating said pivoted carrier toeffect engagement or disengagement of the fixed and movable contacts.

3. In an electric drill switch, the combination with two pair of alignedcircuit making and breaking contacts, of mechanism constructed andarranged to open said contacts together, and a magnetic blow-out coilconnected in circuit with both of said pair of contacts and positionedto blow out arcs formed by them when opened.

4. In an electric drill switch, the combination with a pair ofstationary contacts, a pair of movable contacts associated therewith, acommon blow-out coil between cooperating pairs of said contacts andconnected in series with each pair and adapted to blow out arcs formedthereby, and heat resisting plates of insulating material positionedlaterally of said contacts.

5. In an electric drill switch, the combination with a base plate, of apair of spaced stationary contacts mounted thereon, cooperating movablecontacts therefor, means constructed and arranged to snap saidcooperating contacts open, and a blow-out coil positioned betweencooperating pairs of contacts and connected in series therewith to blowout arcs from each simultaneously when said contacts are opened.

6. In an electric drill switch, the combination with two pairs ofseparable contacts, of a common magnetic blow-out coil positionedbetween and with its ends adjacent to said contacts and connected inseries therewith whereby it is adapted to blow out arcs generated whenvsaid pairs of contacts separate.

7. In an electric drill switch, the combination with two pairs ofcontacts, of means to separate said contacts with a snap action, and asingle magnetic blow-out coil connected in series with said contactshaving a flux concentrating core and positioned to blow out arcs formedby separation of said contacts.

8. In an electric drill switch, the combination with a base ofinsulating material, side protecting plates mounted on said base, acentrally disposed blow-out coil mounted on said base with its endsextending toward and spaced from said plates, and a pair of separablecontacts between each end of said coil and a side plate and connected inseries with said coil.

9. In an electric drill switch, the combination with a base ofinsulating material, of a pair of spaced stationary contacts carriedthereby, a block pivotally mounted on said base, spaced movable contactscarried by said block one cooperating with each stationary contact, aplate positioned from said base, means supporting said plate in spacedrelation to said base, a magnetic 1 blow-out coil mounted between saidbase and plate and positioned and connected to extinguish arcs from bothpairs of cooperating contacts, and snap action mechanism for operatingsaid pivoted block.

10. In an electric drill switch, the combination with a base ofinsulating material, of a pair of spaced stationary contacts carriedthereby, a block pivotally mounted on said base, spaced movable contactscarried by said block one cooperating with each stationary contact, aplate positioned from said base, means supporting said plate in spacedrelation to said base, a magnetic blow-out coil mounted between saidbase and plate and positioned and connected to extinguish arcs from bothpairs of cooperating contacts, and means carried by said plate forlimiting movement of said pivoted block in one direction.

11. In an electric drill switch, the combination with a base ofinsulating material, of a pair of spaced stationary contacts carriedthereby, a block pivotally mounted on said base, spaced movable contactscarried by said block one cooperating with each stationary contact, aplate positioned from said base, means supporting said plate in spacedrelation to said base, a magnetic blow-out coil mounted between saidbase and plate and positioned and connected to extinguish arcs from bothpairs of cooperating contacts, snap action mechanism for operating saidpivoted block, and a stop carried by said plate for limiting movement ofsaid pivoted block in the circuit opening direction.

ROBERT K. JEFFREY.

